1. Technical Field of the Invention
The present invention relates to a direction indicator for a vehicle, and more particularly, to a technique for automatically turning off a flashing turn signal lamp.
In the meantime, in a following description, as a generic name of actions for changing a course of the vehicle such as a right turn, a left turn, a lane change and the like, a term “a course change” is used. Further, a left and a right are used as terms indicating directions as seen from a rear side of a vehicle body.
2. Description of the Related Art
Conventionally there has been known a direction indicator which automatically turns off the flashing turn signal lamp on the basis of a rotating operation of a steering wheel. A direction indicator described in JP, 59-206243 (application number JP 58-080421) is provided with a steering wheel angle sensor detecting an angle of a rotation of the steering wheel. It is possible to flash a turn signal lamp for a right turn or a turn signal lamp for a left turn by setting a turn signal switch to an operation position R for indicating the right turn or an operation position L for indicating the left turn. If the steering wheel turned to the right turn side or the left turn side starts being turned to a reverse direction, the steering wheel angle sensor detects an end of the right turn or the left turn, whereby it is possible to automatically turn off a flashing state of the turn signal lamp.
A direction indicator described in JP, A, 2003-237461 is provided with a rotational amount sensor detecting a rotational amount of a steering wheel. An end of the right turn or the left turn of the vehicle is detected by differentiating by time a detected signal from the rotational amount sensor in a controller. If the end of the right turn or the left turn of the vehicle is detected, it is possible to automatically turn off the flashing state of the turn signal lamp.
The direction indicators described in JP, 59-206243 (application number JP 58-080421) and JP, A, 2003-237461 relate to a technique of automatically turning off the flashing of the turn signal lamp by detecting the rotation angle or the rotational amount of the steering wheel. However, for example, in a construction machine, a fork lift or the like, the steering wheel is not employed for executing a steering operation of the vehicle. In place thereof, a steering operation of the vehicle is executed by using steering means operated in a back and forth direction and a horizontal direction such as a joy stick or the like.
Since the steering wheel is not used in the vehicle steered by the joy stick, it is impossible to automatically turn off the flashing turn signal lamp by detecting the rotation angle or the rotational amount of the steering wheel. Accordingly, it is impossible to use the direction indicators described in JP 59-206243 (application number JP 58-080421) as the direction indicator arranged in the vehicle steered by the joy stick.
Further, comparing the vehicle steered by the Joy stick with the vehicle steered by the steering wheel, for example, with respect to the case of intending to return the right turned wheel to a straight going state on the basis of the end of the right turn, the following differences exist. In other words, since the traveling direction of the vehicle is generally treated as a problem in the vehicle steered by the steering wheel, there is a little problem even if the turn signal lamp for the right turn is turned off at a time of intending to return to the straight going attitude by starting turning the steering wheel from the rotation in the right turn direction to the reverse direction.
On the contrary, in the vehicle steered by the joy stick, it is necessary to give a peripheral worker or the like a warning against the matter the course change from the right turn state to the straight going state is continuously executed. Accordingly, it is required to flash the turn signal lamp so as to issue a warning, for example, until the vehicle is returned to the straight going attitude at a certain degree from the right turn state, in view of a safety for executing the work.